Give Your Envelopes Windows by gracej
It’s a simple idea but man it makes envelopes look more fun! I got the idea from these Drop Around Window Envelopes I saw on UGUiSU. You can use an x-acto knife to cut any shapes you want, just stick a thick folded piece of paper inside the envelope so that you don’t cut all the way through.
I guess the window is technically missing on these but I like them that way (don’t stick anything small in there that could fall out!)